I have plenty of disk space on my home NAS, not so much on my main machine which is also the VM host. So I started looking into iSCSI as my primary means of VM disk storage.
As long as I choose 512 sector sizes for my images, everything works as expected. However, I'm not happy with expected, the performance is far from performance of a volume that is actually on the host (to make the comparison even more unfair, the host has SSDs).
So now I'm wondering if there is maybe a VirtualBox storage filter that would perform R/W caching of my iSCSI volumes.
And if there isn't, are there any guides on how to write one?: I've looked at the code for a bit and it seems documentation for that is a bit sparse. Not to mention I'd be very happy if there was a plugin API, I don't really feel comfortable building my own VirtualBox deployment from scratch.